As conventional polystyrene porous resin beads, those made from a hydroxystyrene-polyene copolymer (JP-A-52-23193, JP-A-58-210914), those made from a copolymer resin obtained by copolymerization of alkoxystyrene, aromatic polyvinyl and an aromatic vinyl compound (JP-A-5-86132 and U.S. Pat. No. 2,987,949) are known. These porous resin beads have been mainly applied as an ion exchange resin, an adsorbent and the like. For such use, adsorption of as much substances as possible is desired. Therefore, the development guideline of conventional porous resin beads includes imparting as many functional groups as possible and enlarging specific surface area as much as possible, with the hope of enhancing substance adsorbability per unit volume of the porous resin beads.